Passive four terminal network for gyrating a current into a voltage



y 8, 1953 B. D. H. TELLEGEN PASSIVE FOUR TERMINAL NETWORK FOR' GYRATINGA CURRENT INTO A VOLTAGE Filed March 6, 1948 E i L L dz FIG. 3b

FIG. 30

l/WE/VZOR.

BERNARDUS D. H. TELLEGEN AGE/VT Patented July 28, 1953 UNITED STATESPATENT 1 OFFICE PASSIVE FOUR TERMINAL NETWORK FOR GYRATING A CURRENTINTOA VOLTAGE Bernardus Dominicus Hubertus-Tellegen, Eindhoven,Netherlands, a'ssignor to Hartford National Bank and Trust Company,Hartford,

Conn., as trustee Application March 6, 1948, Serial No. 13,506

In the Netherlands April 29, 1947 For the impedance elements connectedbetween the terminals of a passive electrical quad- 4 Claims. (01.333-24) ripole or four terminal network use has hitherto wherein thecoeificient n is the transformation ratio if the positive voltages andcurrents correspond to those indicated with the quadripole according toFig. 1 as described more fully hereinafter'.

The properties of quadripolesbuilt up from such network elements may besummarised as follows: a. The relations between the currents passingthrough and the voltages set up across the primary and secondaryterminals may be represented by linear differential equations.

2). The coeflicients of these differential equations are constant; ifthe electrical oscillations are assumed to be sinusoidal and if for thevoltage and the current at the primary and secondary terminals of thequadripole the complex magnitudes V1, I1 and V2, I2 respectively areintroduced, we find as solution of the differential equations betweenthese magnitudes the 'rela-,. tions:

' V1=Z11I1+Z12I2 V2=Z21I1+Z22I2 I (2) the four pole parameters, Z11,Z12, Z21 and Z22 being functions of frequency.

c. The quadripole cannot supply energy.

d. Between the coefiicients of the above quadripole equations thereexists the soecalled reci-.

procity relation:

' Z 12 =Z21.,.. ..W

The invention has for its object to provide, in addition to theaforesaid-network elements, a fifth network element the properties ofwhich conform to'the properties of theother elements, save that theproperty of reciprocity mentioned in the above underd is absent. Thefifth circuit element has the property'of gyrating a current into avoltage and vice versa. In the ideal case for this fifth element thefollowing relations exist between the-instantaneous values of thevoltage set up across and the current passing through the primary andsecondary terminals:

respective if the positive directions are again assumed to be inaccordance with the quadripole shownin Fig. l, the coefficient s havingthe dimension of a resistance.

A network element to which these equations 4 apply, will be referred tohereinafter as ideal gyrator. An ideal gyrator consequently exhibits incontrast to the relation (3) the property that the anti-reciprocityZ12=Zz (5) applies.

In addition to the properties mentioned above under a, b and c, of whichthelatter may be represented by the equation,

are satisfied. ,Herethe proportionality-factor y'X has the same sign, in.contradistinctionto'the relations (4), in which'the proportionalityfactor (5). is of opposite sign." Such 'networksconse-' quently. satisfythereciprocity relation (3) "and drawing wherein:

Fig. 1 is a schematic dia ram illustrating the theory underlying theinvention.

Fig. 2 is a first preferred "embodiment" or a gyrator element inaccordance: with .gthe invention, i

Fig. 3 is a schematic diagrams-illustratingthe method of producing amedium for a gyrator,

Fig. 4 is a second preferred:embodiment pf a gyrator element inaccordance"witlfithaainiaen tion, and

Fig. 5 is a band-pass filter employing a-gyrator element in accordancewith the invention. S The,manner in whicma gwratmr according to the-;invention -may, be ;-reali zed is explained with reference -t0*;-

; -1. Let us -assume that the volta e 1.1 andth i ur n 1. 1.; a :Primary4 other by means of one of these properties of the medium constitutingthe four-pole, this four-pole will be of a certain type.

In the first place this four-pole will or will not satisfy thereciprocity relation. To investigate this we differentiate the Equations('7) with respect to t. The left-hand sides will then become da:/di',-etc. and dJx/ zit;- ,et c. and the right-hand ts-ides weamaymultiplylmywa'w. .iNow dP/dt is a part of a current, dJ/dt is a part ofa voltage,

is a part of a voltage, and H is a part of a current. So, hea ring inmind what has been rsaid-with', reference to Equations (3) and (5)about'the waythe reciprocity relation is ex- ,pressed by equality p1:opposite equality of certain :ffifl 'epole icioeificients, we see thatthose fourspoles: ofswhichxthe terminal pairs are coupled to eachothenby-Ineans of the property of the medium .,repre s ent ed by K, 6,or x, respectively by {terminals l-q-lpf-the quadripolesshowniin Fig.1 9

produce-an-electric;field=having a field strength and: a-magnetic fieldhaving a field strength H1 whereas the. Itage Yi-and the current 12 atthe-secondary;terminalssi l.of the quadripole E2 a -'msenti e1dr h v paa fine-s n t .Hz (for; convenience all-these vectors areishown in thefigure parallel to one another, ;lput,-;-in general, they haveanarbitrary direction with respect to one another). The resultant of the1A. v,;;pr, ,.wi 11, "respectively will not, satisfy the reciprocityrelation of networks.

i Eurthermore, P and E are related to electric pairs of terminals and .1and H to magnetic pairs. h oreyifi. a rau ierm r or; ageysrator could ber z d..-;byrmainl ne-l rvaterminal:pair a y a s foiitone of the; abovementioned 151K, properties hf a di m-couplin by is could lead.-only to adouble electric transformer,

uld l ad Qn t a dou itfitr: syr ter,

v .couldlead only to antelectromagnetic;gyra tpr,

8 .could-=..1ead $01115 ito. an-cl ctrcmagneticyytransformer,

X could lead only to a double-magnetic transformer,

3' could lead only to a double-magnetic gyrator.

According to-the invention, use is -rnade of}, a medium such or, ifdesired, of a medium brought into a state such that ita'exh'ibits theproperty that at least one of:the=--coeiiicients 'y, A, or g is unequalto zero, for if this is the case, it will be possible, by a coupling as,in;:licated1 above between "primary and, aQfSQQQZQQEi-ly. electric. ormagneticfield; tobui'ld upa gyrato1',-.which,.is ida'ljornearlyide'al.

Some examples f 'media'will be discussedawith reference to Figs, z and3; o ne,p ,thesaideoefficients being here 1unequal to ,zero. Fig.4shows" a practical example; of a gyr'ator according to the invention.

R 2 r ts a. s a ot accordinetothe i vention" in-which. f 0r,12h6'medium, use is made of asuhstancegior Whichfthta-cOffiCiRt 3 equal tozero. isuch asubstanceirnay.be'obtained by usingjior'examplefmagneticjmaterial adapted to. he brought. into 'the'ist 'te of saturation ,by, aconstant. magnetic neld 101. .low lfield strength I-Io. Theprimaryterminals l have ccn'nectedto them a fwinding 4, agprimary,rnagneticfield ,of. ,field strength l-Ii being producediby the currentpassing'throu'gh this 'winding '4. fowinglto the gyromagneticefie'ctthecombination or this alternating field H1 and theifield Ho,produces, at right angles to these twoffields at-magnetic alternatingfield Hz which induces in'the winding connected tothe secondaryterminals 2 a voltage which is proportional :to rthecurrenusuDDhedto the:primary terminals I. In order-to guaranteeanwptimumi'ideal'gyratoreifect, it-isf desirable; that theImutual induction betweeri thecoils" land 1 urinal zpairsi-pna four-pale.are coupled to eacli' Fig. 3aillustrates, by way of" example, a method of manufacturing a medium 3for which the coefficient :y is unequalto zero. For

.this purpose a suspension of magnetic material is made in a carrierliquid in which, moreover, an oversaturated solution of a materialhaving a high electrical dipole moment is formed. This film of electricdipole material will now beform'ed around the magnetic dipoles 5 themagnetic and electric polarities having the same or opposite sense. If amedium 3, built up from such a magnetic material wherein the elementarymagnets have at the same time a great magnetic dipole moment and,parallel thereto, a permanent electric dipole moment, is brought betweenthe poles of a magnetic circuit 6, a magnetic fiux will be produced inthe circuit 6, if a current is supplied to the electrodes 8 connected tothe primary terminals I, owing to which the winding 1 connected to theterminals 2 has induced in it a voltage which is proportional to thecurrent supplied to the primary terminals I.

A circuit-arrangement in which the medium has a coefficient which isunequal to zero, may be constructed, for example, in a manner similar tothat shown in Fig. 2, the coils 4 and 1 being replaced by condenserplates.

The invention is not considered to be restricted to gyrators comprisingmedia of which only one of the coefiicients 'Y, A or is unequal to zero;it is possible that at the same time more than one of these coefficientsis unequal to zero. Moreover, some of the coefiicients K X or a will, ingeneral be unequal to zero.

A general property of a quadripole built up with a gyrator is that Z12is unequal to Z21.

Fig. 4 shows one example of application of a gyrator according to theinvention. The primary terminals I of the gyrator 3 are connected to anoscillatory circuit I2 tuned to the central frequency of electricaloscillations to be transmitted, whereas the secondary terminals 2 areconnected to a similar oscillatory circuit I3. The lower terminal I andthe lower terminal 2 are connected to a point of constant potential, andthe upper terminals I and 2 are interconnected for direct-currentthrough a coupling impedance M. It has now been found to be possible todimension the direct-current coupling impedance l4 and the gyratorcoupling 3 in such manner with respect to one another that the circuitbehaves like a bandpass filter. If in this case the gyrator coupling hasthe correct sign with respetc to the direct-current coupling, so thatthe two couplings support one another, it has been found that with asimilar bandwidth and with similar input and output impedances as with aconventional bandpass filter comprising inductively or capacitativelycoupled circuits, the transmission ratio is, with critical coupling, afactor l-|- /2 as great.

If the quadripole shown in Fig. 2 is used as a gyrator, use may be madein a suitable manner of the coils 4 and I for the inductances includedin the circuits l2 and 13.

What I claim is:

1. A passive network comprising a polarized medium, input means tosupply an alternating voltage V1 to said medium to produce analternating current flow I1 in said input means, output means coupled tosaid medium to obtain an alternating voltage V2 producing a current flowIs in said output means, said medium possessing gyroma neticcharacteristics and including rnaterial having an anisotropicpolarization property wherein: .V1=-.'SI2.

Where S is a-constantfl 2. A passive four-terminal network comprisingapolarizable medium possessing gyromagnetic properties, input terminalsto apply an input voltage and an input current to said network, outputterminals to take an output voltage and an output current from saidnetwork, means to polarize said medium in a firstdirection, meansconnected to said input terminals to produce a primary field in saidmedium in a second direction different from said first direction, saidprimary field producing in said polarized medium a secondary fieldhaving a third direction difierent from said first and seconddirections, and means coupled to saidsecondary field to produce saidoutput voltage and output current at said output terminals.

3. A circuit arrangement having a passive four-terminal networkcomprising a polarizable medium possessing gyromagnetic properties,input terminals to apply an input voltage and an input current to saidnetwork, output terminals to take an output voltage and an outputcurrent from said network, means to polarize said medium in a firstdirection, means connected to said input terminals to produce a primaryfield in, said medium in a second direction different from said firstdirection, said primary field producing in said polarized medium asecondary field having a third direction different from said first andsecond directions, and means coupled to said secondary field to producesaid output voltage and output current at said output terminals, therelation between said input voltage V1, said input current I1, saidoutput voltage V2 and said output current 12 being wherein Z11 is theinput impedance of the network, Z22 is the output impedance of thenetwork and Z21 and Z12 are transfer impedances having unequalmagnitude.

4. A passive four terminal network comprising -a polarized mediumpossessing gyromagnetic properties, said medium being polarized in a,first direction, input terminals to apply an input voltage and an inputcurrent to said network, output terminals to take an output voltage andan output current from said network, means connected to said inputterminals to produce a. primary field in said medium in a seconddirection difierent from said first direction, said primary fieldproducing in said polarized medium a secondary field having a thirddirection different from said first and second directions, and meanscoupled to said secondary field to produce said output voltage andoutput current at said output terminals.

BERNARDUS DOMINICUS HUBERTUS TELLEGEN.

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